Method for testing or screening protein synthesis inhibitors

ABSTRACT

This invention provides methods for screening an inhibitor of protein synthesis by measuring the level of relocalization of an SMN complex component from the cytoplasm to the nucleus. Additionally, the invention provides a kit and a system for screening protein synthesis inhibitors in a cell.

FIELD OF INVENTION

This invention provides: methods, kits, and systems for testing protein synthesis inhibitors.

BACKGROUND OF THE INVENTION

Translation is the RNA directed synthesis of polypeptides. This process requires all three classes of RNA. Although the chemistry of peptide bond formation is relatively simple, the processes leading to the ability to form a peptide bond are exceedingly complex. The template for correct addition of individual amino acids is the mRNA, yet both tRNAs and rRNAs are involved in the process. The tRNAs carry activated amino acids into the ribosome which is composed of rRNA and ribosomal proteins. The ribosome is associated with the mRNA ensuring correct access of activated tRNAs and containing the necessary enzymatic activities to catalyze peptide bond formation.

Regulation of this information pathway can be achieved at a number of levels, including the modulation of translation factor levels or activity, ribosome biogenesis, and small molecule/RNA interactions. Small molecule ligands that inhibit the process of translation provide exquisite insight into ribosome function and translation factor activity in both prokaryotes and eukaryotes.

Inhibitors targeting a specific step of protein synthesis enable dissection of the translation pathway by allowing the characterization of events leading to the assembly of active polysomes, trapping intermediates of the initiation and elongation cycle, and providing insight into the molecular functions of protein factors.

Deregulation of protein synthesis is a major contributor in cancer initiation and metastatic progression. Overexpression of some initiation factors can lead to malignant transformation, whereas down-regulation of these same factors can suppress the transformed phenotype. In cancers components of the translation apparatus are overexpressed or mutated. For example, the tumor suppressor gene product pRB directly impacts on the translation process by affecting the levels of ribosomes. Furthermore, key components of anti-apoptotic pathways are translationally regulated.

Thus, protein synthesis represents a valid target for chemotherapeutic intervention. Few inhibitors of protein synthesis have been tested in clinical trials, with some of these demonstrating encouraging therapeutic effects. Presumably, a therapeutic index is achieved due to the higher requirement of transformed cells for protein synthesis, as well as translation regulation of some of the proteins involved in cancer progression. Unfortunately, dose-limiting secondary effects have hampered further development of many of these compounds.

SUMMARY OF THE INVENTION

This invention provides, in one embodiment, a method for testing a candidate compound for an ability to inhibit protein synthesis in a cell, comprising the steps of: contacting a cell with a candidate compound; and measuring the level of a SMN complex component in the cytoplasm of a cell, the nucleus of a cell, or a combination thereof, whereby, if a candidate compound increases the amount of the SMN complex component in the nucleus, decreases the amount of the SMN complex component in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, the present invention provides a method for screening or testing a library of compounds for ability to treat a disease associated with protein synthesis inhibition, wherein the disease is selected from a viral disease, cancer, or a neurodegenerative disease, comprising the steps of: contacting a cell with a test compound, and measuring the level of an SMN complex component relocalization from the cytoplasm to the nucleus, whereby, if the test compound causes relocalization of a SMN complex component from the cytoplasm to the nucleus, then the test compound has an ability to treat the disease associated with protein synthesis inhibition.

In another embodiment, the present invention provides a kit for screening or testing potential protein synthesis inhibitors in a cell, comprising a reagent for measuring a level of an SMN complex component in the nucleus of the cell, the cytoplasm of the cell, or a combination thereof.

In another embodiment, the present invention provides a system for screening or testing protein synthesis inhibitors in a cell, comprising a kit for measuring protein synthesis inhibitors in a cell, comprising an SMN complex component relocalization measuring reagents.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

FIG. 1A shows an immunostaining micrograph [×40] of SMN following treatment with RNAi of a non-targeting siRNA (A), following RNAi of SMN (B), RNAi of Gemin2 (C), RNAi of Gemin3 (D), RNAi of Gemin4 (E) and RNAi of Gemin5 (F). FIG. 1B depicts a bar graph which represents quantitation of the average anti-SMN (2B1) antibody signal intensities per Gem (black bars) and the average numbers of Gems per cell (white bars) of the images shown in FIG. 1A.

FIG. 2A and FIG. 2B shows an immunostaining micrograph [×20] identifying alterations in SMN sub-cellular localization. FIG. 2A shows immunostaining of SMN in DMSO-treated cells. FIG. 2B shows immunostaining of SMN in cells treated for 4 hours with a compound from the library that was identified as having a significant change in SMN sub-cellular distribution. FIG. 2C shows a bar graph which represents quantitation of the average changes in cytoplasmic fluorescence intensity in control (DMSO treated cells) (black bars) and in cells treated for 4 hours with a compound having a significant change in SMN sub-cellular distribution (white bars).

FIG. 3A shows an immunostaining micrograph of SMN in control HeLa PV cells and following treatment with 10 μM cycloheximide (CHX) for the indicated times. Control cells were treated with DMSO at the same final concentration as that used to dissolve CHX. FIG. 3B shows a microscopic immunostaining micrograph of SMN localization in HeLa cells treated with 5-20 μM cycloheximide and immunostained after 4 hours of treatment. FIG. 3C shows a microscopic immunostaining micrograph of FXR1, PABP, hnRNP A1 and Sm proteins (snRNPs) in control HeLa cells (upper panel) and after 6 hrs of 10 μM CHX treatment (lower panel).

FIG. 4 shows an immunostaining micrograph of sub-cellular localization of an SMN complex component in control HeLa cells and in CHX treated cells. Immunostaining of Gemins 2, 3, 5, 6 and 7 in control DMSO treated cells is shown in the upper panel. Immunostaining of Gemins 2, 3, 5, 6 and 7 in cells treated for 6 hours with 10 μM CHX is shown in the lower panel.

FIG. 5 shows an immunostaining micrograph of sub-cellular localization of an SMN complex component in control HeLa cells and in HDAC inhibitors treated cells. FIG. 5A shows immunostaining of SMN in DMSO treated cells (control) and in cells treated with 2 μM TSA, 7.5 mM VPA, 8 μM scriptaid, 10 μM HDAC inhibitor 1 and 5 μM apicidin for 24 hours. FIG. 5B shows immunostaining of SMN in HeLa cells treated with 2-10 mM VPA. FIG. 5C shows immunostaining of Gemins 2, 3, 5, and 6 in control cells (upper panel) and in cells treated for 24 hrs with 10 mM VPA (lower panel).

FIG. 6 shows an immunostaining micrograph of SMN localization. FIG. 6 a is immunostaining of SMN in control HeLa cells (left panel) and in cells treated with an inactive analogue of cycloheximide, cycloheximide-N-ethylethanoate (CHX-N) at 10 μM. FIG. 6 b is immunostaining of SMN showing nuclear accumulation in cells treated with 10 μM emetine, 10 μM puromycin, 10 μM thapsigargin and 10 μg/ml tunicamycin, as depicted on the panels.

FIG. 7 shows an immunostaining micrograph of SMN localization in HeLa PV cells stably transfected with a non-targeting shRNA (upper panels) and in cells stably transfected with an shRNA targeting SMN (lower panels). Both cell lines were treated with DMSO as control at the same final concentration as that used to dissolve CHX and following treatment with 10 μM cycloheximide (CHX) for 6 hours as indicated.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, the present invention provides a method for testing an ability of a compound to inhibit protein synthesis, comprising the steps of contacting a cell with the compound and measuring the level of SMN complex in the cytoplasm of the cell, the nucleus of the cell, or a combination thereof, whereby, if the compound increases the amount of the SMN complex in the nucleus, decreases the amount of the SMN complex in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, relocalization of a SMN complex component from the cytoplasm to the nucleus is measured. In another embodiment, calculating a change in distribution of an SMN complex component in the cytoplasm and the nucleus of a cell comprises measuring the level of relocalization of a SMN complex component from the cytoplasm to the nucleus. In another embodiment, calculating a change in distribution of an SMN complex component in the cytoplasm and the nucleus of a cell comprises measuring the distribution of an SMN complex component in the cytoplasm and the nucleus in a cell. Each possibility represents a separate embodiment of the present invention.

In one embodiment, the present invention provides a method for screening or testing a library of compounds for an inhibitor of protein synthesis, comprising the steps of contacting a plurality of cells or cell samples with potential inhibitors of protein synthesis, and measuring the level of SMN complex in the cytoplasm of the cell, the nucleus of the cell, or a combination thereof, whereby, if a compound in the library increases the amount of the SMN complex in the nucleus, decreases the amount of the SMN complex in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, each of the cells or cell samples is contacted with a different compound from the library. In another embodiment, relocalization of a SMN complex component from the cytoplasm to the nucleus is measured. In another embodiment, measuring relocalization of a SMN complex component from the cytoplasm to the nucleus comprises calculating a change in distribution of an SMN complex component in the cytoplasm and the nucleus of a cell. In another embodiment, calculating a change in distribution of an SMN complex component in the cytoplasm and the nucleus of a cell comprises measuring the distribution of an SMN complex component in the cytoplasm and the nucleus in a cell. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the SMN complex component is a Gem. In another embodiment, Gems are discrete SMN complex bodies in the nucleus. In another embodiment, “SMN complex components” comprise, in addition to SMN, other proteins termed “Gemins.”

In another embodiment, the Gemin protein is Gemin 1 protein. In another embodiment, the sequence of the Gemin1 protein comprises the sequence:

(SEQ. ID NO: 1) MAMSSGGSGGGVPEQEDSVLFRRGTGQSDDSDIWDDTALIKAYDKAVASF KHALKNGDICETSGKPKTTPKRKPAKKNKSQKKNTAASLQQWKVGDKCSA IWSEDGCIYPATIASIDFKRETCVVVYTGYGNREEQNLSDLLSPICEVAN NIEQNAQENENESQVSTDESENSRSPGNKSDNIKPKSAPWNSFLPPPPPM PGPRLGPGKPGLKFNGPPPPPPPPPPHLLSCWLPPFPSGPPIIPPPPPIC PDSLDDADALGSMLISWYMSGYHTGYYMGFRQNQKEGRCSHSLN. In another embodiment, the Gemin 1 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 1. In another embodiment, the Gemin 1 protein is a Homo sapiens Gemin1 protein. In another embodiment, the Gemin1 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin2 protein. In another embodiment, the sequence of the Gemin2 protein comprises the sequence:

(SEQ. ID NO: 2) MRRAELAGLKTMAWVPAESAVEELMPRLLPVEPCDLTEGFDPSVPPRTPQ EYLRRVQIEAAQCPDVVVAQIDPKKLKRKQSVNISLSGCQPAPEGYSPTL QWQQQQVAQFSTVRQNVNKHRSHWKSQQLDSNVTMPKSEDEEGWKKFCLG EKLCADGAVGPATNESPGIDYVQIGFPPLLSIVSRMNQATVTSVLEYLSN WFGERDETPELGRWLYALLACLEKPLLPEAHSLIRQLARRCSEVRLLVDS KDDERVPALNLLICLVSRYFDQRDLADEPS.  In another embodiment, the Gemin2 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 2. In another embodiment, the Gemin2 protein is a Homo sapiens Gemin2 protein. In another embodiment, the Gemin2 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin3 protein. In another embodiment, the sequence of the Gemin3 protein comprises the sequence:

(SEQ. ID NO: 3) MAAAFEASGALAAVATAMPAEHVAVQVPAPEPTPGPVRILRTAQDLSSPR TRTGDVLLAEPADFESLLLSRPVLEGLRAAGFERPSPVQLKAIPLGRCGL DLIVQAKSGTGKTCVFSTIALDSLVLENLSTQILILAPTREIAVQIHSVI TAIGIKMEGLECHVFIGGTPLSQDKTRLKKCHIAVGSPGRIKQLIELDYL NPGSIRLFILDEADKLLEEGSFQEQINWIYSSLPASKQMLAVSATYPEFL ANALTKYMRDPTFVRLNSSDPSLIGLKQYYKVVNSYPLAHKVFEEKTQHL QELFSRIPFNQALVFSNLHSRAQHLADILSSKGFPAECISGNMNQNQRLD AMAKLKHFHCRVLISTDLTSRGIDAEKVNLVVNLDVPLDWETYMHRIGRA GRFGTLGLTVTYCCRGEEENMMMRIAQKCNINLLPLPDPIPSGLMEECVD WDVEVKAAVHTYGIASVPNQPLKKQIQKIERTLQIQKAHGDHMASSRNNS VSGLSVKSKNNTKQKLPVKSHSECGIIEKATSPKELGCDRQSEEQMKNSV QTPVENSTNSQHQVKEALPVSLPQIPCLSSFKIHQPYTLTFAELVEDYEH YIKEGLEKPVEIIRHYTGPGDQTVNPQNGFVRNKVIEQRVPVLASSSQSG DSESDSDSYSSRTSSQSKGNKSYLEGSSDNQLKDSESTPVDDRISLEQPP NGSDTPNPEKYQESPGIQMKTRLKEGASQRAKQSRRNLPRRSSFRLQTEA QEDDWYDCHREIRLSFSDTYQDYEEYWRAYYRAWQEYYAAASHSYYWNAQ RHPSWMAAYHMNTIYLQEMMHSNQ.  In another embodiment, the Gemin3 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 3. In another embodiment, the Gemin3 protein is a Homo sapiens Gemin3 protein. In another embodiment, the Gemin3 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin4 protein. In another embodiment, the sequence of the Gemin4 protein comprises the sequence:

(SEQ. ID NO: 4) MDLGPLNICEEMTILHGGFLLAEQLFHPKALAELTKSDWERVGRPIVEAL REISSAAAHSQPFAWKKKALIIIWAKVLQPHPVTPSDTETRWQEDLFFSV GNMIPTINHTILFELLKSLEASGLFIQLLMALPTTICHAELERFLEHVTV DTSAEDVAFFLDIWWEVMKHKGHPQDPLLSQFSAMAHKYLPALDEFPHPP KRLRSDPDACPTMPLLAMLLRGLTQIQSRILGPGRKCCALANLADMLTVF ALTEDDPQEVSATVYLDKLATVISVWNSDTQNPYHQQALAEKVKEAERDV SLTSLAKLPSETIFVGCEFLHHLLREWGEELQAVLRSSQGTSYDSYRLCD SLTSFSQNATLYLNRTSLSKEDRQVVSELAECVRDFLRKTSTVLKNRALE DITASIAMAVIQQKMDRHMEVCYIFASEKKWAFSDEWVACLGSNRALFRE PDLVLRLLETVIDVSTADRAIPESQIRQVIHLILECYADLSLPGKNKVLA GILRSWGRKGLSEKLLAYVEGFQEDLNTTFNQLTQSASEQGLAKAVASVA RLVIVHPEVTVKKMCSLAVVNLGTHKFLAQILTAFPALRFVEVQGPNSSA TFMVSCLKETVWMKFSTPKEEKQFLELLNCLMSPVKPQGIPVAALLEPDE VLKEFVLPFLRLDVEEVDLSLRIFIQTLEANACREEYWLQTCSPFPLLFS LCQLLDRFSKYWPLPKEKRCLSLDRKDLAIHILELLCEIVSANAETFSPD VWIKSLSWLHRKLEQLDWTVGLRLKSFFEGHFKCEVPATLFEICKLSEDE WTSQAHPGYGAGTGLLAWMECCCVSSGISERMLSLLVVDVGNPEEVRLFS KGFLVALVQVMPWCSPQEWQRLHQLTRRLLEKQLLHVPYSLEYIQFVPLL NLKPFAQELQLSVLFLRTFQFLCSHSCRNWLPLEGWNHVVKLLCGSLTRL LDSVRAIQAAGPWVQGPEQDLTQEALFVYTQVFCHALHIMAMLHPEVCEP LYVLALETLTCYETLSKTNPSVSSLLQRAHEQRFLKSIAEGIGPEERRQT LLQKMSSF.  In another embodiment, the Gemin4 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 4. In another embodiment, the Gemin4 protein is a Homo sapiens Gemin4 protein. In another embodiment, the Gemin4 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin5 protein. In another embodiment, the sequence of the Gemin5 protein comprises the sequence:

(SEQ. ID NO: 5) MGQEPRTLPPSPNWYCARCSDAVPGGLFGFAARTSVFLVRVGPGAGESPG TPPFRVIGELVGHTERVSGFTFSHHPGQYNLCATSSDDGTVKIWDVETKT VVTEHALHQHTISTLHWSPRVKDLIVSGDEKGVVFCYWFNRNDSQHLFIE PRTIFCLTCSPHHEDLVAIGYKDGIVVIIDISKKGEVIHRLRGHDDEIHS IAWCPLPGEDCLSINQEETSEEAEITNGNAVAQAPVTKGCYLATGSKDQT IRIWSCSRGRGVMILKLPFLKRRGGGIDPTVKERLWLTLHWPSNQPTQLV SSCFGGELLQWDLTQSWRRKYTLFSASSEGQNHSRIVFNLCPLQTEDDKQ LLLSTSMDRDVKCWDIATLECSWTLPSLGGFAYSLAFSSVDIGSLAIGVG DGMIRVWNTLSIKNNYDVKNFWQGVKSKVTALCWHPTKEGCLAFGTDDGK VGLYDTYSNKPPQISSTYHKKTVYTLAWGPPVPPMSLGGEGDRPSLALYS CGGEGIVLQHNPWKLSGEAFDINKLIRDTNSIKYKLPVHTEISWKADGKI MALGNEDGSIEIFQIPNLKLICTIQQHHKLVNTISWHHEHGSQPELSYLM ASGSNNAVIYVHNLKTVIESSPESPVTITEPYRTLSGHTAKITSVAWSPH HDGRLVSASYDGTAQVWDALREEPLCNFRGHRGRLLCVAWSPLDPDCIYS GADDFCVHKWLTSMQDHSRPPQGKKSIELEKKRLSQPKAKPKKKKKPTLR TPVKLESIDGNEEESMKENSGPVENGVSDQEGEEQAREPELPCGLAPAVS REPVICTPVSSGFEKSKVTINNKVILLKICEPPKEKPETLIKKRKARSLL PLSTSLDHRSKEELHQDCLVLATAKHSRELNEDVSADVEERFHLGLFTDR ATLYRMIDIEGKGHLENGHPELFHQLMLWKGDLKGVLQTAAERGELTDNL VAMAPAAGYHVWLWAVEAFAKQLCFQDQYVKAASHLLSIHKVYEAVELLK SNHFYREAIAIAKARLRPEDPVLKDLYLSWGTVLERDGHYAVAAKCYLGA TCAYDAAKVLAKKGDAASLRTAAELAAIVGEDELSASLALRCAQELLLAN NWVGAQEALQLHESLQGQRLVFCLLELLSRHLEEKQLSEGKSSSSYHTWN TGTEGPFVERVTAVWKSIFSLDTPEQYQEAFQKLQNIKYPSATNNTPAKQ LLLHICHDLTLAVLSQQMASWDEAVQALLRAVVRSYDSGSFTIMQEVYSA FLPDGCDHLRDKLGDHQSPATPAFKSLEAFFLYGRLYEFWWSLSRPCPNS SVWVRAGHRTLSVEPSQQLDTASTEETDPETSQPEPNRPSELDLRLTEEG ERMLSTFKELFSEKHASLQNSQRTVAEVQETLAEM1RQHQKSQLCKSTAN GPDKNEPEVEAEQPLCSSQSQCKEEKNEPLSLPELTKRLTEANQRMAKFP ESIKAWPFPDVLECCLVLLLIRSHFPGCLAQEMQQQAQELLQKYGNTKTY RRHCQTFCM.  In another embodiment, the Gemin5 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 5. In another embodiment, the Gemin5 protein is a Homo sapiens Gemin5 protein. In another embodiment, the Gemin5 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin6 protein. In another embodiment, the sequence of the Gemin6 protein comprises the sequence:

(SEQ. ID NO: 6) MSEWMKKGPLEWQDYIYKEVRVTASEKNEYKGWVLTTDPVSANIVLVNFL EDGSMSVTGIMGHAVQTVETMNEGDHRVREKLMHLFTSGDCKAYSPEDLE ERKNSLKKWLEKNHIPITEQGDAPRTLCVAGVLTIDPPYGPENCSSSNEI ILSRVQDLIEGHLTASQ.  In another embodiment, the Gemin6 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 6. In another embodiment, the Gemin6 protein is a Homo sapiens Gemin6 protein. In another embodiment, the Gemin6 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein is Gemin7 protein. In another embodiment, the sequence of the Gemin7 protein comprises the sequence:

(SEQ. ID NO: 7) MQTPVNIPVPVLRLPRGPDGFSRGFAPDGRRAPLRPEVPEIQECPIAQES LESQEQRARAALRERYLRSLLAMVGHQVSFTLHEGVRVAAHFGATDLDVA NFYVSQLQTPIGVQAEALLRCSDIISTYTFKP.  In another embodiment, the Gemin7 protein of the present invention comprises an amino acid sequence homologous to SEQ. ID. NO: 7. In another embodiment, the Gemin7 protein is a Homo sapiens Gemin7 protein. In another embodiment, the Gemin7 protein is from a non-human species. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein of the present invention is a mouse Gemin. In another embodiment, the Gemin protein of the present invention is a rat Gemin. In another embodiment, the Gemin protein of the present invention is a Drosophila melanogaster Gemin. In another embodiment, the Gemin protein of the present invention is a baboon Gemin. In another embodiment, the Gemin protein of the present invention is a guinea pig Gemin. In another embodiment, the Gemin protein of the present invention is a Drosophila melanogaster Gemin. In another embodiment, the Gemin protein is from any other species known in the art. Each possibility represents a separate embodiment of the present invention.

In another embodiment, the Gemin protein of the present invention is at least 60% homologous to anyone SEQ. ID NOs: 1-7. In another embodiment, the Gemin protein of the present invention is at least 70% homologous to anyone SEQ. ID NOs: 1-7. In another embodiment, the Gemin protein of the present invention is at least 80% homologous to anyone SEQ. ID NOs: 1-7. In another embodiment, the Gemin protein of the present invention is at least 90% homologous to anyone SEQ. ID NOs: 1-7. In another embodiment, the Gemin protein of the present invention is at least 95% homologous to anyone SEQ. ID NOs: 1-7.

In another embodiment, protein synthesis according to the present invention comprises the multi-step process comprising the translation of the genetic information encoded in messenger RNAs (mRNAs) into proteins. In another embodiment, the method of the present invention is based on cellular localization of the survival of motor neurons protein (SMN). In another embodiment, protein synthesis inhibitors cause the SMN complex (and several of its Gemins) to relocalize from the cytoplasm to the nucleus. In another embodiment, protein synthesis inhibitors cause the SMN associated proteins to relocalize from the cytoplasm to the nucleus. In another embodiment, SMN associated proteins are Gemins.

In another embodiment, the SMN protein of the present invention oligomerizes and forms a stable multiprotein complex that comprises of SMN, Gemin2 (SIP1), Gemin3 (a DEAD-box RNA helicase), Gemin4, Gemin5 (a WD-repeat protein), Gemin6 and Gemin7. In another embodiment, SMN protein binds directly to Gemin 2, 3, 5 and 7, whereas Gemin 4 and 6 require Gemin3 and 7, respectively, for interaction with SMN. In another embodiment, other proteins bind to SMN protein.

In another embodiment, these proteins, referred to as SMN complex substrates, include Sm and Sm-like (LSm) proteins, RNA helicase A, fibrillarin and GAR1, the RNP proteins hnRNP U, hnRNP Q and hnRNP R, as well as p80-coilin, the protein marker for Cajal (coiled) bodies.

In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 1-48 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 1-3 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 3-5 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 5-7 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 7-9 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 4-6 hours.

In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 9-12 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 12-15 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 15-18 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 18-21 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 21-24 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 24-30 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 30-36 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 36-42 hours. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 42-48 hours.

In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 1-8 hours in HeLa cells. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 2-7 hours in HeLa cells. In another embodiment, protein synthesis inhibitors cause the SMN protein and/or Gemins to relocalize from the cytoplasm to the nucleus within 4-6 hours in HeLa cells.

In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 0.1 μM-100 mM (example 3). In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 0.1-4 μM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 0.1-0.5 p M. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 1-2 μM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 2-3 μM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 3-5 μM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 5-10 μM.

In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 10-100 μM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 100 μM-1 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 1-5 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 5-15 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 15-30 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 30-50 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 50-75 mM. In another embodiment, the candidate compound screened or tested according to the methods of the present invention is applied in a concentration of 75-100 mM.

In another embodiment, the method of the present invention is carried out using cells cultured in miniaturized format. In another embodiment, cells cultured in miniaturized format of the present invention comprise multi-well plates. In another embodiment, a multi-well plate of the present invention comprises 96 wells. In another embodiment, a multi-well plate of the present invention comprises 384 wells (example 2). In another embodiment, a multi-well plate of the present invention comprises 1536 wells. In another embodiment, a multi-well plate of the present invention comprises from 2-5000 wells. In another embodiment, a multi-well plate of the present invention comprises from 20-3000 wells. In another embodiment, a multi-well plate of the present invention comprises from 96-2000 wells.

In another embodiment, the cells of the present invention are treated for several hours as indicated hereinabove in the presence of compounds that potentially inhibit protein synthesis (example 3). In another embodiment, the cells of the present invention are treated in the presence of small molecules that potentially inhibit protein synthesis. In another embodiment, the cells of the present invention are then fixed. In another embodiment, the cells of the present invention are further permeabilized. In another embodiment, the cells of the present invention are further contacted with an SMN specific ligand. In another embodiment, the SMN specific ligand labels the SMC complex components. In another embodiment, the SMN specific ligand labels SMC complex component.

In another embodiment, the labeled SMN complex component is then detected. In another embodiment, the labeled SMN complex component is then detected by microscopy. In another embodiment, digital images record the microscopic images. In another embodiment, the digital images are collected from several fields in each well. In another embodiment, the microscopic images collected from several fields in each well are further analyzed by algorithmic imaging software. In another embodiment, the algorithmic imaging software monitors the amount of labeled an SMN complex component in the nucleus. In another embodiment, the algorithmic imaging software monitors the relative amount of labeled an SMN complex component in the nucleus. In another embodiment, the nucleus is defined by the signal of a nuclear specific stain. In another embodiment, the cytoplasm is defined by the signal of a cytoplasmic specific stain. In another embodiment, the nucleus signal is collected in a separate channel from the labeled an SMN complex component (example 2).

In another embodiment, the present invention provides method identifying inhibitors of protein translation. In another embodiment, a method for identifying inhibitors of protein translation can avoid dysregulated, protein synthesis in disease. In another embodiment, a method for identifying inhibitors of protein translation can avoid enhanced protein synthesis in disease. In another embodiment, the ribosome recruitment phase of translation initiation is usurped in many human cancers. In another embodiment, the protein synthesis inhibitors identified by the methods of the present invention block signaling events promoting cancer.

In another embodiment, the present invention provides method for identifying inhibitors of protein elongation. In another embodiment, inhibitors of protein elongation have direct consequence of protein synthesis inhibition. In another embodiment, inhibitors of protein elongation identified by the methods of the present invention are anti-cancer agents. In another embodiment, inhibitors of protein synthesis of the present invention target ABL protein. In another embodiment, inhibitors of protein synthesis of the present invention target PDGFR protein. In another embodiment, inhibitors of protein synthesis of the present invention target KIT protein.

In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat breast cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat prostate cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can leukemia. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat chronic myeloid leukemia. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat skin cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat colorectal cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat premalignant polyps. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat mammary adenocarcinoma. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat mantle cell lymphoma. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat oral squamous cell carcinoma. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat pancreatic tumors. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat bladder cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat lung cancer. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat gastrointestinal tumors. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat head tumors. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat neck tumors. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat Hodgkin's lymphoma. In another embodiment, inhibitors of protein synthesis identified by the methods of the present invention can treat neuroblastoma.

In another embodiment, inhibitors of protein synthesis of the present invention are screened or tested on a primary cell culture derived from a tumor. In another embodiment, inhibitors of protein synthesis of the present invention are screened or tested on a primary cell culture derived from a cancer patient suffering from one of the cancers listed hereinabove. In another embodiment, inhibitors of protein synthesis of the present invention are screened or tested on a cancer cell line. In another embodiment, inhibitors of protein synthesis of the present invention are screened or tested on a cancer cell line of a hematopoietic lineage.

In another embodiment, the methods of the present invention are preformed on a cell.

In another embodiment, the cell of the present invention is a eukaryotic cell. In another embodiment, the cell of the present invention is an epidermal keratinocyte. In another embodiment, the cell of the present invention is an epidermal basal cell. In another embodiment, the cell of the present invention is a keratinocyte of fingernails or toenails. In another embodiment, the cell of the present invention is a nail bed basal cell. In another embodiment, the cell of the present invention is a stem cell. In another embodiment, the cell of the present invention is a medullary hair shaft cell. In another embodiment, the cell of the present invention is a cortical hair shaft cell. In another embodiment, the cell of the present invention is a cuticular hair shaft cell. In another embodiment, the cell of the present invention is a cuticular hair root sheath cell. In another embodiment, the cell of the present invention is a hair root sheath cell of Huxley's layer. In another embodiment, the cell of the present invention is a hair root sheath cell of Henle's layer. In another embodiment, the cell of the present invention is an external hair root sheath cell. In another embodiment, the cell of the present invention is a hair matrix cell. In another embodiment, the cell of the present invention is a prokaryotic cell.

In another embodiment, the cell of the present invention is a wet stratified barrier epithelial cell. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the cornea. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the tongue. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the oral cavity. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the esophagus. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the anal canal. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the distal urethra. In another embodiment, the cell of the present invention is a surface epithelial cell of stratified squamous epithelium of the vagina.

In another embodiment, the cell of the present invention is a basal cell of epithelia of the cornea. In another embodiment, the cell of the present invention is a basal cell of epithelia of the tongue. In another embodiment, the cell of the present invention is a basal cell of epithelia of the oral cavity. In another embodiment, the cell of the present invention is a basal cell of epithelia of the esophagus. In another embodiment, the cell of the present invention is a basal cell of epithelia of the anal canal. In another embodiment, the cell of the present invention is a basal cell of epithelia of the distal urethra. In another embodiment, the cell of the present invention is a basal cell of epithelia of the vagina.

In another embodiment, the cell of the present invention is a urinary epithelium cell. In another embodiment, the cell of the present invention is an exocrine secretory epithelial cell. In another embodiment, the cell of the present invention is a salivary gland mucous cell. In another embodiment, the cell of the present invention is a salivary gland serous cell. In another embodiment, the cell of the present invention is a Von Ebner's gland cell. In another embodiment, the cell of the present invention is a mammary gland cell. In another embodiment, the cell of the present invention is a lacrimal gland cell. In another embodiment, the cell of the present invention is a ceruminous gland cell. In another embodiment, the cell of the present invention is an eccrine sweat gland dark cell. In another embodiment, the cell of the present invention is an eccrine sweat gland clear cell. In another embodiment, the cell of the present invention is an apocrine sweat gland cell. In another embodiment, the cell of the present invention is a gland of moll cell. In another embodiment, the cell of the present invention is a sebaceous gland cell. In another embodiment, the cell of the present invention is a Bowman's gland cell. In another embodiment, the cell of the present invention is a Brunner's gland cell. In another embodiment, the cell of the present invention is a seminal vesicle cell. In another embodiment, the cell of the present invention is a prostate gland cell. In another embodiment, the cell of the present invention is a bulbourethral gland cell. In another embodiment, the cell of the present invention is a Bartholin's gland cell. In another embodiment, the cell of the present invention is a gland of Littre cell. In another embodiment, the cell of the present invention is a uterus endometrium cell. In another embodiment, the cell of the present invention is a goblet cell. In another embodiment, the cell of the present invention is a stomach lining mucous cell.

In another embodiment, the cell of the present invention is a gastric gland cell. In another embodiment, the cell of the present invention is a gastric gland zymogenic cell. In another embodiment, the cell of the present invention is a gastric gland oxyntic cell. In another embodiment, the cell of the present invention is a pancreatic cell. In another embodiment, the cell of the present invention is a pancreatic acinar cell. In another embodiment, the cell of the present invention is a paneth cell. In another embodiment, the cell of the present invention is a pneumocyte. In another embodiment, the cell of the present invention is a Clara cell of lung.

In another embodiment, the cell of the present invention is a hormone secreting cell. In another embodiment, the cell of the present invention is an anterior pituitary cell. In another embodiment, the cell of the present invention is a somatotrope. In another embodiment, the cell of the present invention is a lactotrope. In another embodiment, the cell of the present invention is a thyrotrope. In another embodiment, the cell of the present invention is a gonadotrope. In another embodiment, the cell of the present invention is a corticotrope. In another embodiment, the cell of the present invention is an intermediate pituitary cell. In another embodiment, the cell of the present invention is a magnocellular neurosecretory cell. In another embodiment, the cell of the present invention is an oxytocin secreting cell. In another embodiment, the cell of the present invention is a serotonin secreting cell. In another embodiment, the cell of the present invention is an endorphin secreting cell. In another embodiment, the cell of the present invention is a somatostatin secreting cell. In another embodiment, the cell of the present invention is a gastrin secreting cell. In another embodiment, the cell of the present invention is a secretin secreting cell. In another embodiment, the cell of the present invention is a cholecystokinin secreting cell. In another embodiment, the cell of the present invention is an insulin secreting cell. In another embodiment, the cell of the present invention is a glucagon secreting cell. In another embodiment, the cell of the present invention is a bombesin secreting cell. In another embodiment, the cell of the present invention is a thyroid gland cell. In another embodiment, the cell of the present invention is a thyroid epithelial cell. In another embodiment, the cell of the present invention is a parafollicular cell. In another embodiment, the cell of the present invention is a parathyroid gland cell. In another embodiment, the cell of the present invention is a parathyroid chief cell. In another embodiment, the cell of the present invention is an oxyphil cell.

In another embodiment, the cell of the present invention is an adrenal gland cell. In another embodiment, the cell of the present invention is a chromaffin cell. In another embodiment, the cell of the present invention is a steroid hormones secreting cell. In another embodiment, the cell of the present invention is a Leydig cell. In another embodiment, the cell of the present invention is a theca interna cell. In another embodiment, the cell of the present invention is a corpus luteum cell. In another embodiment, the cell of the present invention is a kidney juxtaglomerular apparatus cell. In another embodiment, the cell of the present invention is a macula densa cell. In another embodiment, the cell of the present invention is a peripolar cell. In another embodiment, the cell of the present invention is a mesangial cell. In another embodiment, the cell of the present invention is an intestinal brush border cell. In another embodiment, the cell of the present invention is an exocrine gland striated duct cell. In another embodiment, the cell of the present invention is a gall bladder epithelial cell. In another embodiment, the cell of the present invention is a kidney proximal tubule brush border cell. In another embodiment, the cell of the present invention is a kidney distal tubule cell. In another embodiment, the cell of the present invention is a ductulus efferens nonciliated cell. In another embodiment, the cell of the present invention is an epididymal principal cell. In another embodiment, the cell of the present invention is an epididymal basal cell.

In another embodiment, the cell of the present invention is a storage cell. In another embodiment, the cell of the present invention is a hepatocyte. In another embodiment, the cell of the present invention is a white fat cell. In another embodiment, the cell of the present invention is a brown fat cell. In another embodiment, the cell of the present invention is a liver lipocyte.

In another embodiment, the cell of the present invention is a barrier function cell. In another embodiment, the cell of the present invention is a type I pneumocyte. In another embodiment, the cell of the present invention is a pancreatic duct cell. In another embodiment, the cell of the present invention is a nonstriated duct cell. In another embodiment, the cell of the present invention is a kidney glomerulus parietal cell. In another embodiment, the cell of the present invention is a kidney glomerulus podocyte. In another embodiment, the cell of the present invention is a loop of Henle thin segment cell. In another embodiment, the cell of the present invention is a kidney collecting duct cell. In another embodiment, the cell of the present invention is a duct cell. In another embodiment, the cell of the present invention is an epithelial cell lining closed internal body cavity. In another embodiment, the cell of the present invention is a blood vessel cell. In another embodiment, the cell of the present invention is a lymphatic vascular endothelial fenestrated cell. In another embodiment, the cell of the present invention is a blood vessel or lymphatic vascular endothelial continuous cell. In another embodiment, the cell of the present invention is a blood vessel or lymphatic vascular endothelial splenic cell. In another embodiment, the cell of the present invention is a synovial cell. In another embodiment, the cell of the present invention is a serosal cell. In another embodiment, the cell of the present invention is a squamous cell. In another embodiment, the cell of the present invention is a columnar cell of endolymphatic sac with microvilli. In another embodiment, the cell of the present invention is a columnar cell of endolymphatic sac without microvilli. In another embodiment, the cell of the present invention is a dark cell. In another embodiment, the cell of the present invention is a vestibular membrane cell. In another embodiment, the cell of the present invention is a stria vascularis basal cell. In another embodiment, the cell of the present invention is a stria vascularis marginal cell. In another embodiment, the cell of the present invention is a cell of Claudius. In another embodiment, the cell of the present invention is a cell of Boettcher. In another embodiment, the cell of the present invention is a choroid plexus cell. In another embodiment, the cell of the present invention is a pia-arachnoid squamous cell. In another embodiment, the cell of the present invention is a pigmented ciliary epithelium cell. In another embodiment, the cell of the present invention is a nonpigmented ciliary epithelium cell. In another embodiment, the cell of the present invention is a corneal endothelial cell. In another embodiment, the cell of the present invention is a ciliated cell with propulsive function. In another embodiment, the cell of the present invention is a respiratory tract ciliated cell. In another embodiment, the cell of the present invention is an oviduct ciliated cell. In another embodiment, the cell of the present invention is a uterine endometrial ciliated cell. In another embodiment, the cell of the present invention is a rete testis cilated cell. In another embodiment, the cell of the present invention is a ductulus efferens ciliated cell. In another embodiment, the cell of the present invention is a ciliated ependymal cell of central nervous system.

In another embodiment, the cell of the present invention is an extracellular matrix secretion cell. In another embodiment, the cell of the present invention is an ameloblast epithelial cell. In another embodiment, the cell of the present invention is a planum semilunatum epithelial cell. In another embodiment, the cell of the present invention is an organ of Corti interdental epithelial cell. In another embodiment, the cell of the present invention is a fibroblast. In another embodiment, the cell of the present invention is a loose connective tissue fibroblast. In another embodiment, the cell of the present invention is a corneal fibroblast. In another embodiment, the cell of the present invention is a tendon fibroblast. In another embodiment, the cell of the present invention is a bone marrow reticular tissue fibroblast. In another embodiment, the cell of the present invention is a nonepithelial fibroblast. In another embodiment, the cell of the present invention is a pericyte. In another embodiment, the cell of the present invention is a nucleus pulposus cell of intervertebral disc. In another embodiment, the cell of the present invention is a cementoblast. In another embodiment, the cell of the present invention is a cementocyte. In another embodiment, the cell of the present invention is an odontoblast. In another embodiment, the cell of the present invention is an odontocyte.

In another embodiment, the cell of the present invention is a chondrocyte. In another embodiment, the cell of the present invention is a hyaline cartilage chondrocyte. In another embodiment, the cell of the present invention is a fibrocartilage chondrocyte. In another embodiment, the cell of the present invention is an elastic cartilage chondrocyte. In another embodiment, the cell of the present invention is an osteoblast. In another embodiment, the cell of the present invention is an osteocyte. In another embodiment, the cell of the present invention is an osteoprogenitor cell. In another embodiment, the cell of the present invention is a hyalocyte. In another embodiment, the cell of the present invention is a stellate cell. In another embodiment, the cell of the present invention is a contractile cell.

In another embodiment, the cell of the present invention is a muscle cell. In another embodiment, the cell of the present invention is a red skeletal muscle cell. In another embodiment, the cell of the present invention is a white skeletal muscle cell. In another embodiment, the cell of the present invention is an intermediate skeletal muscle cell. In another embodiment, the cell of the present invention is a nuclear bag cell. In another embodiment, the cell of the present invention is a nuclear chain cell. In another embodiment, the cell of the present invention is a satellite cell. In another embodiment, the cell of the present invention is a heart muscle cell. In another embodiment, the cell of the present invention is a nodal heart muscle cell. In another embodiment, the cell of the present invention is a purkinje fiber cell. In another embodiment, the cell of the present invention is a smooth muscle cell. In another embodiment, the cell of the present invention is a myoepithelial cell.

In another embodiment, the cell of the present invention is a blood cell. In another embodiment, the cell of the present invention is an immune system cell. In another embodiment, the cell of the present invention is a red blood cell. In another embodiment, the cell of the present invention is a megakaryocyte. In another embodiment, the cell of the present invention is a monocyte. In another embodiment, the cell of the present invention is macrophage. In another embodiment, the cell of the present invention is an epidermal Langerhans cell. In another embodiment, the cell of the present invention is an osteoclast. In another embodiment, the cell of the present invention is a dendritic cell. In another embodiment, the cell of the present invention is a microglial cell. In another embodiment, the cell of the present invention is a neutrophil. In another embodiment, the cell of the present invention is an eosinophil. In another embodiment, the cell of the present invention is a basophile. In another embodiment, the cell of the present invention is a mast cell.

In another embodiment, the cell of the present invention is a T-Helper cell. In another embodiment, the cell of the present invention is a T-suppressor cell. In another embodiment, the cell of the present invention is a cytotoxic T cell. In another embodiment, the cell of the present invention is a B cell. In another embodiment, the cell of the present invention is a natural killer cell. In another embodiment, the cell of the present invention is a reticulocyte. In another embodiment, the cell of the present invention is a stem cell. In another embodiment, the cell of the present invention is a committed progenitor for the blood and immune system.

In another embodiment, the cell of the present invention is a sensory transducer cell. In another embodiment, the cell of the present invention is an auditory inner hair cell of organ of Corti. In another embodiment, the cell of the present invention is an auditory outer hair cell of organ of Corti. In another embodiment, the cell of the present invention is a basal olfactory epithelium cell. In another embodiment, the cell of the present invention is a cold-sensitive primary sensory neuron. In another embodiment, the cell of the present invention is a heat-sensitive primary sensory neuron. In another embodiment, the cell of the present invention is a merkel cell. In another embodiment, the cell of the present invention is an olfactory receptor neuron. In another embodiment, the cell of the present invention is a pain-sensitive primary sensory neuron. In another embodiment, the cell of the present invention is a photoreceptor rod cell. In another embodiment, the cell of the present invention is a photoreceptor blue-sensitive cone cell. In another embodiment, the cell of the present invention is a photoreceptor green-sensitive cone cell. In another embodiment, the cell of the present invention is a photoreceptor red-sensitive cone cell. In another embodiment, the cell of the present invention is a proprioceptive primary sensory neuron. In another embodiment, the cell of the present invention is a touch-sensitive primary sensory neuron. In another embodiment, the cell of the present invention is a type I carotid body cell. In another embodiment, the cell of the present invention is a type II carotid body cell. In another embodiment, the cell of the present invention is a type I hair cell of vestibular apparatus. In another embodiment, the cell of the present invention is a type H hair cell of vestibular apparatus. In another embodiment, the cell of the present invention is a type I taste bud cell. In another embodiment, the cell of the present invention is an autonomic neuron cell. In another embodiment, the cell of the present invention is a cholinergic neural cell. In another embodiment, the cell of the present invention is an adrenergic neural cell. In another embodiment, the cell of the present invention is a peptidergic neural cell. In another embodiment, the cell of the present invention is a sense organ or peripheral neuron supporting cell. In another embodiment, the cell of the present invention is an inner pillar cell of organ of Corti. In another embodiment, the cell of the present invention is an outer pillar cell of organ of Corti. In another embodiment, the cell of the present invention is an inner phalangeal cell of organ of Corti. In another embodiment, the cell of the present invention is an outer phalangeal cell of organ of Corti. In another embodiment, the cell of the present invention is a border cell of organ of Corti. In another embodiment, the cell of the present invention is a Hensen cell of organ of Corti. In another embodiment, the cell of the present invention is a vestibular apparatus supporting cell. In another embodiment, the cell of the present invention is a type I taste bud supporting cell. In another embodiment, the cell of the present invention is an olfactory epithelium supporting cell. In another embodiment, the cell of the present invention is a Schwann cell. In another embodiment, the cell of the present invention is a satellite cell encapsulating peripheral nerve cell bodies. In another embodiment, the cell of the present invention is an enteric glial cell.

In another embodiment, the cell of the present invention is a central nervous system neuron. In another embodiment, the cell of the present invention is a glial cell. In another embodiment, the cell of the present invention is an astrocyte. In another embodiment, the cell of the present invention is an oligodendrocyte. In another embodiment, the cell of the present invention is a spindle neuron. In another embodiment, the cell of the present invention is a lens cell. In another embodiment, the cell of the present invention is an anterior lens epithelial cell. In another embodiment, the cell of the present invention is a crystalline-containing lens fiber cell. In another embodiment, the cell of the present invention is a karan cell. In another embodiment, the cell of the present invention is a pigment cell. In another embodiment, the cell of the present invention is a melanocyte. In another embodiment, the cell of the present invention is a retinal pigmented epithelial cell.

In another embodiment, the cell of the present invention is a germ cell. In another embodiment, the cell of the present invention is an oogonium. In another embodiment, the cell of the present invention is an oocyte. In another embodiment, the cell of the present invention is a spermatid. In another embodiment, the cell of the present invention is a spermatocyte. In another embodiment, the cell of the present invention is a spermatogonium cell. In another embodiment, the cell of the present invention is a spermatozoon.

In another embodiment, the cell of the present invention is a nurse cell. In another embodiment, the cell of the present invention is an ovarian follicle cell. In another embodiment, the cell of the present invention is a sertoli cell. In another embodiment, the cell of the present invention is a thymus epithelial cell.

In another embodiment, the cell of the present invention is derived from an organ. In another embodiment, the cell of the present invention is derived from a tissue. In another embodiment, the cell of the present invention is derived from a cell line. In another embodiment, the cell of the present invention is derived from a primary cell culture. In another embodiment, the cell of the present invention is a HeLa cell. In another embodiment, the cell of the present invention is a U2OS cell.

In another embodiment, the cell of the present invention is a plant cell. In another embodiment, the cell of the present invention is an invertebrate cell. In another embodiment, the cell of the present invention is a vertebrate cell. In another embodiment, the cell of the present invention is an insect cell. In another embodiment, the cell of the present invention is an amphibian cell. In another embodiment, the cell of the present invention is a reptile cell. In another embodiment, the cell of the present invention is a mammalian cell.

In another embodiment, the present invention provides a tissue section in which individual cells are analyzed.

In one embodiment, the present invention provides a method for the selective capture of a SMN complex component with a ligand. In another embodiment, the ligand of the invention binds Gem. In another embodiment, the ligand of the invention selectively binds Gem. In another embodiment, the ligand of the invention binds a Gemin protein. In another embodiment, the ligand of the invention selectively binds a Gemin protein.

In another embodiment, the ligand of the present invention is an antibody.

In another embodiment, the ligand is a polyclonal antibody. In another embodiment, the ligand is a monoclonal antibody. In another embodiment, the monoclonal antibody is a monovalent Fab fragments. In another embodiment, the monoclonal antibody is a Bivalent mini-antibodies (equivalent to F(ab′)2 fragments). In another embodiment, the monoclonal antibody is comprised of a genetic fusion to a variety of common protein tags.

In another embodiment, the antibody of the present invention is a multiple engineered specificity antibody. In another embodiment, bispecific antibodies contain two different binding specificities fused together. In another embodiment, bispecific antibodies of the invention bind to two adjacent epitopes on a single target antigen. In another embodiment, bispecific antibodies of the invention bind to two adjacent epitopes on the SMN complex. In another embodiment, bispecific antibodies of the invention cross-link two different antigens. In another embodiment, Bispecific antibodies of the present invention are produced by fusion of two hybridoma cell lines into a single ‘quadroma’ cell line. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate either chemical conjugation. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate either genetic conjugation. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate fusion to adhesive heterodimeric domains.

In another embodiment, the antibody of the present invention is a bifunctional antibodie. In another embodiment, the antibody of the present invention is fused to radio labeled moiety. In another embodiment, the antibody of the present invention is fused to an enzyme.

In another embodiment, the antibody of the present invention is derived from antibody libraries. In another embodiment, the antibody of the present invention is a specific high-affinity antibody selected by linking phenotype (binding affinity) to genotype, thereby allowing simultaneous recovery of the gene encoding the selected antibody.

In another embodiment, the antibody of the present invention is comprised of single-chain Fv fragments. In another embodiment, the single-chain Fv fragments antibody of the present invention contain a complete binding site and consist of the individual heavy and light chain V domain (12-14 kDa each). In another embodiment, the single-chain Fv fragments antibody of the present invention is linked to a single protein by a hydrophilic and flexible polypeptide linker. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally include also a His tag. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally includes an immuno-detection epitope. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally includes a protease specific cleavage site. In another embodiment, the linker of the variable region domains (carboxyl ter-minus of the VL sequence to the amino terminus of the VH sequence) has to be long enough to span the distance from the C-terminus of one domain to the N-terminus of the second domain (about 3.5 nm).

In another embodiment, the antibody according to the methods of the present invention binds a protein within the SMN complex. In another embodiment, the antibody according to the methods of the present invention is a monoclonal anti-SMN protein antibody. In another embodiment, the antibody according to the methods of the present invention is the anti-SMN monoclonal antibody 2B1. In another embodiment, the 2B1 antibody of the present invention binds Gems. In another, embodiment, 2B1 antibody binds cytoplasmic Gems. In another, embodiment, 2B1 antibody binds nuclear Gems (See example 1). In another embodiment, the antibody of the present invention binds Gemin1. In another embodiment, the antibody of the present invention binds Gemin2. In another embodiment, the antibody of the present invention binds Gemin3. In another embodiment, the antibody of the present invention binds Gemin4. In another embodiment, the antibody of the present invention binds Gemin5. In another embodiment, the antibody of the present invention binds Gemin6. In another embodiment, the antibody of the present invention binds Gemin7 (example 5, FIG. 4).

In another embodiment, the ligand of the present invention is labeled.

In another embodiment, the antibody of the present invention is labeled. In another embodiment, the labeled antibody of the present invention is a fluorescent labeled antibody. In another embodiment, the label is Alexa Fluor. In another embodiment, the label is green fluorescent protein. In another embodiment, the label is Oregon green. In another embodiment, the label is Emerald. In another embodiment, the label is Azami Green. In another embodiment, the label is ZsGreen 1. In another embodiment, the label is a blue fluorescent protein. In another embodiment, the label is EBFP. In another embodiment, the label is Sapphire. In another embodiment, the label is a cyan fluorescent protein. In another embodiment, the label is cerulean. In another embodiment, the label is ECFP. In another embodiment, the label is AmCyan. In another embodiment, the label is Midoriishi-Cyan. In another embodiment, the label is a yellow fluorescent protein. In another embodiment, the label is ZsYellow1. In another embodiment, the label is PhiYFP. In another embodiment, the label is Citrine. In another embodiment, the label is Venus. In another embodiment, the label is an orange fluorescent protein. In another embodiment, the label is Kusabira-Orange. In another embodiment, the label is mOrange. In another embodiment, the label is a red fluorescent protein. In another embodiment, the label is DsRed. In another embodiment, the label is HcRed. In another embodiment, the label is mPlum. In another embodiment, the label is mRaspberry. In another embodiment, the label is mTomato. In another embodiment, the label is mStrawberry. In another embodiment, the label is green-to-red fluorescent Dendra.

In another embodiment, the present invention provides a SMN complex component is fused to a fluorescent probe.

In another embodiment, an identifiable gene product serves as a distinguishable marker for a SMN complex component. In another embodiment, the methods of the present invention provide a Gemin protein fused to a fluorescent probe of the invention. In another embodiment, the methods of the present invention provide that a SMN complex component is a chimera comprising a SMN complex component and a fluorescent protein.

In another embodiment, the label of the present invention is a radioactive label. In another embodiment, a ligand of the present invention is radioactively labeled with ³²P. In another embodiment, an antibody of the present invention is radioactively labeled with ³²P. In another embodiment, a ligand of the present invention is radioactively labeled with ¹²⁵I. In another embodiment, an antibody of the present invention is radioactively labeled with ¹²⁵I. In another embodiment, the label of the present invention is a chemiluminescent label. In another embodiment, the label of the present invention is a gold label.

In some embodiments, the detection method is indirect comprising a ligand of the present invention similar to immunohistochemical probes as known to one skilled in the art. In another embodiment, probes may be labeled with hapten or biotin used to bring an enzyme which creates a detectable event (e.g., chemiluminescent, colorimetric or fluorescent) to the SMN complex component site. In another embodiment, wherein amplification of the detection signal is required, a secondary labeled antibody specifically identifying the primary antibody is utilized. In another embodiment, the methods utilizing a specific probe comprising an antibody enable selective identification of an SMN component.

In another embodiment, the method of the present invention provides measuring the level of an SMN complex component relocalization from the cytoplasm to the nucleus. In another embodiment, the method of the present invention provides measuring an SMN complex component in the nucleus and cytoplasm of said cell. In another embodiment, the method of the present invention provides an absolute number of an SMN complex component in the nucleus and cytoplasm.

In another embodiment, the present invention provides a method of testing a candidate compound for an ability to inhibit protein synthesis, comprising the steps of contacting a cell with a candidate compound; and measuring the level of a SMN complex component in the cytoplasm of a cell, the nucleus of a cell, or a combination thereof, whereby, if a candidate compound increases the amount of the SMN complex component in the nucleus, decreases the amount of the SMN complex component in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, the present invention further provides detection of pro-apoptotic cell derived compounds (e.g. hormones, growth factors, nitric oxide, or cytokines) that are measured according to methods known to one of skill in the art. In another embodiment, inhibition of protein synthesis is measured according to the methods of the present invention in cells secreting pro-apoptotic compounds. In another embodiment, induction of protein synthesis is measured according to the methods of the present invention in cells secreting pro-apoptotic compounds. In another embodiment, inhibition of protein synthesis is measured according to the methods of the present invention in cells undergoing apoptosis. In another embodiment, induction of protein synthesis is measured according to the methods of the present invention in cells undergoing apoptosis.

In another embodiment, ability to decrease protein synthesis correlates with ability to induce the expression of pro-apoptotic cytokines or hormones in a target cell. In another embodiment, ability to decrease protein synthesis correlates with ability to induce the pro-apoptotic oxidative stress in a target cell. In another embodiment, ability to inhibit protein synthesis correlates with ability to induce the expression of pro-apoptotic cytokines or hormones in a target cell. In another embodiment, ability to induce protein synthesis correlates with ability to induce the expression of pro-apoptotic cytokines or hormones in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce the expression of pro-apoptotic cytokines or hormones in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce pro-apoptotic oxidative stress in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce pro-apoptotic nitric oxide (NO) stress in a target cell.

In another embodiment, induction of apoptosis by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, induction of expression of pro-apoptotic cytokines in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of apoptosis by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of expression of pro-apoptotic cytokines or hormones in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of pro-apoptotic NO in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis.

In another embodiment, the present invention provides a method of testing a candidate compound for an ability to inhibit protein synthesis dependent necrosis, comprising the steps of contacting a cell with a candidate compound; and measuring the level of a SMN complex component in the cytoplasm of a cell, the nucleus of a cell, or a combination thereof, whereby, if a candidate compound increases the amount of the SMN complex component in the nucleus, decreases the amount of the SMN complex component in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, the present invention further provides detection of pro-necrotic cell derived compounds (e.g. hormones, growth factors, nitric oxide, or cytokines) that are measured according to methods known to one of skill in the art. In another embodiment, protein synthesis inhibition or induction is measured according to the methods of the present invention in cells undergoing necrosis. In another embodiment, induction protein synthesis is measured according to the methods of the present invention in cells undergoing necrosis.

In another embodiment, ability to decrease protein synthesis correlates with ability to induce stress in a target cell. In another embodiment, ability to decrease protein synthesis correlates with ability to induce oxidative stress in a target cell. In another embodiment, ability to decrease protein synthesis correlates with ability to induce hypoxia in a target cell. In another embodiment, ability to decrease protein synthesis correlates with starving a target cell. In another embodiment, ability to decrease protein synthesis correlates with ability to induce necrosis in a target cell. In another embodiment, ability to inhibit protein synthesis correlates with ability to induce necrosis in a target cell.

In another embodiment, ability to increase protein synthesis correlates with ability to induce stress in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce oxidative stress in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce hypoxia in a target cell. In another embodiment, ability to increase protein synthesis correlates with starving a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce necrosis in a target cell.

In another embodiment, induction of necrosis by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, induction of expression of pro-necrotic cytokines in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of necrosis by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of expression of pro-necrotic cytokines or hormones in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis.

In another embodiment, the present invention provides a method of testing a candidate compound for an ability to inhibit protein synthesis dependent inflammation, comprising the steps of contacting a cell with a candidate compound; and measuring the level of a SMN complex component in the cytoplasm of a cell, the nucleus of a cell, or a combination thereof, whereby, if a candidate compound increases the amount of the SMN complex component in the nucleus, decreases the amount of the SMN complex component in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis. In another embodiment, the present invention further provides detection of pro-inflammatory cell derived compounds (e.g. IL-1, IL-6, TNF-α, and TGF-β) that are measured according to methods known to one of skill in the art.

In another embodiment, inhibition of protein synthesis is measured according to the methods of the present invention in cells secreting pro-inflammatory compounds. In another embodiment, induction of protein synthesis is measured according to the methods of the present invention in cells secreting pro-inflammatory compounds. In another embodiment, ability to decrease protein synthesis correlates with ability to induce the expression of pro-inflammatory cytokines in a target cell. In another embodiment, ability to inhibit protein synthesis correlates with ability to induce the expression of pro-inflammatory cytokines in a target cell. In another embodiment, ability to induce protein synthesis correlates with ability to induce the expression of pro-inflammatory cytokines in a target cell. In another embodiment, ability to increase protein synthesis correlates with ability to induce the expression of pro-inflammatory cytokines in a target cell.

In another embodiment, induction of inflammation by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, induction of expression of pro-inflammatory cytokines in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of inflammation by a candidate compound of the present invention correlates with a steady state level of protein synthesis. In another embodiment, inhibition of expression of pro-inflammatory cytokines in a target cell by a candidate compound of the present invention correlates with a steady state level of protein synthesis.

In another embodiment, the method of the present invention provides a method for screening for an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring a level of an SMN complex component in the cytoplasm. In another embodiment, the method of the present invention provides a method for testing an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring a level of an SMN complex component in the cytoplasm. In another embodiment, the method of the present invention further provides setting a threshold level of an SMN complex component in the cytoplasm in steady state (control treatment (FIG. 2)). In another embodiment, the method of the present invention provides that contacting a cell with a protein synthesis inhibitor causes a decline in the levels of an SMN complex component in the cytoplasm of the treated cells compared to the control cells.

In another embodiment, the method of the present invention provides a method for screening for an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring an SMN complex component in the nucleus. In another embodiment, the method of the present invention provides a method for testing an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring an SMN complex component in the nucleus.

In another embodiment, the present invention provides a method for screening for an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring an SMN complex component in the nucleus. In another embodiment, the present invention provides a method for testing an inhibitor of protein synthesis, comprising the steps of contacting a cell with a candidate compound and measuring an SMN complex component in the nucleus. In another embodiment, the method of the present invention further provides setting a threshold level of an SMN complex component in the nucleus in steady state (control treatment (FIG. 2)). In another embodiment, the method of the present invention provides that contacting a cell with a protein synthesis inhibitor causes an incline in the levels of an SMN complex component in the nucleus of the treated cells compared to the control cells.

In one embodiment, the invention provides a method of identifying SMN complex components, which comprises visualizing the probed SMN complex components. In another embodiment, visualization of an SMN complex component is carried out by exposing the labeled specimen to a film. In another embodiment, visualization of an SMN complex component is performed using a fluorescent microscope. In another embodiment, visualization of an SMN complex component is performed using a confocal microscope. In another embodiment, visualization of an SMN complex component is performed using a transmission electron microscope (TEM). In another embodiment, visualization of an SMN complex component is performed using a scanning electron microscope (SEM). In another embodiment, visualization of an SMN complex component is performed using a reflection electron microscope (REM). In another embodiment, visualization of an SMN complex component is performed using a scanning transmission electron microscope (STEM). In another embodiment, a light microscope is used for visualization of SMN complex components, while in another embodiment; the signal is detectable using the naked eye. In another embodiment, the results of the above mentioned visualization methods can be further recorded and/or visualized on a charge-coupled device (CCD) camera. In another embodiment, a back-illuminated, cooled, CCD camera is used for luminescent detection. In another embodiment, color CCD cameras as well as dual-photon lasers are used for ultra-high-resolution imaging of a fluorescent protein.

In another embodiment, the invention provides means of quantifying the probed SMN complex components.

In another embodiment, quantification is assessed by a fluorometer. In another embodiment digital images are collected. In another embodiment digital images are collected from at least two fields in each well. In another embodiment digital images are collected from at least three fields in each well. In another embodiment digital images are collected from at least four fields in each well. In another embodiment digital images are collected from at least four fields in each well. In another embodiment digital images are collected from at least five fields in each well. In another embodiment digital images are collected from six fields in each well (example 2).

In another embodiment, the methods of the present invention provide means of analyzing the digital images of the invention.

In another embodiment, means of analyzing the digital images comprise computer software based on algorithms for multiple parameters. In another embodiment, the methods of the present invention provide that multiple parameters comprise at least two parameters. In another embodiment, the multiple parameters comprise nuclear and cytoplasmic florescence intensities (example 2). In another embodiment, the multiple parameters comprise relative nuclear and cytoplasmic florescent intensities (example 2). In another embodiment, the multiple parameters comprise nuclear and cytoplasmic chemiluminescent or gold label intensities. In another embodiment, the multiple parameters comprise nuclear and cytoplasmic radioactive label intensities.

In another embodiment, multiple parameters further comprise number, size and signal intensity of a SMA complex component. In another embodiment, multiple parameters further comprise number, size and signal intensity of Gems.

In another embodiment, chemiluminescent detection comprises an enzyme which provides enzymatic amplification. In another embodiment, the enzyme which provides enzymatic amplification is horseradish peroxidase. In another embodiment, the enzyme which provides enzymatic amplification is alkaline phosphatase. In another embodiment, the enzyme which provides enzymatic amplification is β-galactosidase.

In another embodiment, the method of the present invention provides nucleus boundaries identification. In another embodiment, the method of the present invention provides that nucleus boundaries are identified according to nuclear membrane staining. In another embodiment, the method of the present invention provides a separate channel to define the boundary of each nucleus. In another embodiment, the method of the present invention provides that DAPI-stained images are collected in a separate channel to define the boundary of each nucleus (example 1). In another embodiment a change in SMN sub-cellular localization is examined directly (FIG. 2).

In another embodiment, the present invention provides a method of quantitatively measuring the amount of a SMN complex component in the nucleus and in the cytoplasm.

In another embodiment, the present invention provides a method for comparative assessment of the amounts of a SMN complex component in the nucleus and in the cytoplasm. In another embodiment, the present invention provides a method for comparative assessment of the relative amounts of a SMN complex component in the nucleus and in the cytoplasm.

In another embodiment, the present invention provides a method for screening a library of compounds for ability to treat a disease associated with protein synthesis inhibition, comprising the steps of contacting a plurality of cells or cell samples with potential inhibitors of protein synthesis, and measuring the level of SMN complex in the cytoplasm of the cell, the nucleus of the cell, or a combination thereof, whereby, if a compound in the library increases the amount of the SMN complex in the nucleus, decreases the amount of the SMN complex in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis. In another embodiment, the present invention provides a method for testing a library of compounds for ability to treat a disease associated with protein synthesis inhibition, comprising the steps of contacting a plurality of cells or cell samples with potential inhibitors of protein synthesis, and measuring the level of SMN complex in the cytoplasm of the cell, the nucleus of the cell, or a combination thereof, whereby, if a compound in the library increases the amount of the SMN complex in the nucleus, decreases the amount of the SMN complex in the cytoplasm, or a combination thereof, then the compound exhibits an ability to inhibit protein synthesis.

In another embodiment, the disease associated with protein synthesis inhibition is Alzheimer's disease. In another embodiment, protein synthesis is significantly altered in Alzheimer's disease. In another embodiment this impairments contributes to Alzheimer's disease pathogenesis. In another embodiment, the disease associated with protein synthesis inhibition is mild cognitive impairment. In another embodiment, protein synthesis inhibition is a factor in regulating whether cells maintain homeostasis in response to oxidative damage, or conversely whether oxidative stress is induced by oxidative damage.

In another embodiment, the disease associated with protein synthesis inhibition is a viral disease. In another embodiment, the virus inhibits protein synthesis in the host cell. In another embodiment, the disease associated with protein synthesis inhibition is Newcastle disease. In another embodiment, Newcastle disease is induced by Newcastle disease virus-(NDV). In another embodiment, NDV induces inhibition of host cell protein and RNA synthesis.

In another embodiment, a picornavirus virus inhibits protein synthesis in a host cell. In another embodiment, the disease associated with protein synthesis inhibition is polio. In another embodiment, polio disease is induced by poliovirus. In another embodiment, poliovirus induces inhibition of host cell protein synthesis.

In another embodiment, the disease associated with protein synthesis inhibition is cancer. In another embodiment, the cancer associated with protein synthesis inhibition is breast cancer. In another embodiment, metastatic breast carcinomas are associated with protein synthesis inhibition. In another embodiment, metastatic breast carcinomas in lymph nodes are associated with protein synthesis inhibition.

In another embodiment, the present invention provides a kit for measuring protein synthesis inhibitors in a cell. In another embodiment, the kit of present invention comprises an SMN complex component relocalization measuring reagents.

In another embodiment, the kit of present invention comprises a ligand selective for a SMN complex component.

In another embodiment, the kit of present invention comprises an SMN complex component relocalization measuring reagents. In another embodiment, the kit of present invention comprises a ligand selectively capturing a SMN complex component. In another embodiment, the ligand of the invention binds Gem. In another embodiment, the ligand of the invention specifically binds a Gemin protein.

In another embodiment, the kit of the present invention comprises an antibody.

In another embodiment the kit of the present invention comprises a polyclonal antibody. In another embodiment, the kit of the present invention comprises a monoclonal antibody. In another embodiment, the kit of the present invention comprises a monovalent Fab fragments. In another embodiment, the kit of the present invention comprises a Bivalent mini-antibody.

In another embodiment, the kit of the present invention comprises a multiple engineered specificity antibody. In another embodiment, the kit of the present invention comprises a bispecific antibodies which contain two different binding specificities fused together. In another embodiment, bispecific antibodies of the invention bind to two adjacent epitopes on a single target antigen. In another embodiment, bispecific antibodies of the invention bind to two adjacent epitopes on the SMA complex. In another embodiment, bispecific antibodies of the invention cross-link two different antigens. In another embodiment, bispecific antibodies of the present invention are produced by fusion of two hybridoma cell lines into a single ‘quadroma’ cell line. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate chemical conjugation. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate genetic conjugation. In another embodiment, effective methods to couple two different Fab modules of the invention incorporate fusion to adhesive heterodimeric domains.

In another embodiment, the kit of the present invention comprises a bifunctional antibody. In another embodiment, the antibody of the present invention is fused to radio labeled moiety. In another embodiment, the antibody of the present invention is fused to an enzyme.

In another embodiment, the kit of the present invention comprises an antibody derived from antibody libraries. In another embodiment, the kit of the present invention comprises an antibody which is a specific high-affinity antibody selected by linking phenotype (binding affinity) to genotype, thereby allowing simultaneous recovery of the gene encoding the selected antibody.

In another embodiment, the kit of the present invention comprises an antibody composed of a single-chain Fv fragments. In another embodiment, the single-chain Fv fragments antibody of the present invention contain a complete binding site and consist of the individual heavy and light chain V domain. In another embodiment, the single-chain Fv fragments antibody of the present invention is linked to a single protein by a hydrophilic and flexible polypeptide linker. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally include also a His tag. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally includes an immunodetection epitope. In another embodiment, the single-chain Fv fragments antibody of the present invention additionally includes a protease specific cleavage site. In another embodiment, the linker of the variable region domains (carboxyl ter-minus of the VL sequence to the amino terminus of the VH sequence) has to be long enough to span the distance from the C-terminus of one domain to the N-terminus of the second domain (about 3.5 nm).

In another embodiment, the kit of the present invention comprises an antibody which binds a protein within the SMN complex. In another embodiment, the kit of the present invention comprises a monoclonal anti-SMN component antibody. In another embodiment, the kit of the present invention comprises an anti-SMN monoclonal 2B1 antibody. In another embodiment, the kit of the present invention comprises 2B1 antibody which binds Gems. In another embodiment, the kit of the present invention comprises 2B1 antibody which binds cytoplasmic Gems. In another, embodiment, the kit of the present invention comprises 2B1 antibody which binds nuclear Gems. In another embodiment, the kit of the present invention comprises an anti-Gemin1 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin1 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin2 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin3 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin4 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin5 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin6 antibody. In another embodiment, the kit of the present invention comprises an anti-Gemin7 antibody.

In another embodiment, the kit of the present invention comprises a labeled ligand. In another embodiment, the kit of the present invention comprises a labeled antibody. In another embodiment, the labeled antibody is a fluorescent labeled antibody as described hereinabove.

In another embodiment, the kit of the present invention comprises a plasmid encoding a SMN complex component fused to a fluorescent probe. In another embodiment, the fluorescent probe is selected from the fluorescent proteins described hereinabove. In another embodiment, plasmid comprises a Gemin protein fused to a fluorescent probe of the invention.

In another embodiment, the kit of the present invention comprises a radioactive label. In another embodiment, the kit of the present invention comprises a ligand radioactively labeled with ³²P. In another embodiment, the kit of the present invention comprises an antibody radioactively labeled with ³²P. In another embodiment, the kit of the present invention comprises a ligand radioactively labeled with ¹²⁵I. In another embodiment, the kit of the present invention comprises an antibody radioactively labeled with ¹²⁵I. In another embodiment, the kit of the present invention comprises a ligand attached to chemiluminescent label. In another embodiment, the kit of the present invention comprises an antibody attached to a chemiluminescent label. In another embodiment, the kit of the present invention comprises a ligand conjugated to a chemiluminescent label. In another embodiment, the kit of the present invention comprises an antibody conjugated to a chemiluminescent label. In another embodiment, the kit of the present invention comprises a ligand conjugated to a gold label. In another embodiment, the kit of the present invention comprises an antibody conjugated to a gold label.

In another embodiment, the kit of the present invention comprises buffers. In another embodiment, buffers of the present invention comprise the reagents of the present invention. In another embodiment, the kit of the present invention comprises cell fixation reagents. In another embodiment, the fixation reagent of the present invention is an alcohol. In another embodiment, the fixation reagent of the present invention is methanol. In another embodiment, the fixation reagent of the present invention is ethanol. In another embodiment, the fixation reagent of the present invention is paraformaldehyde. In another embodiment, the fixation reagent of the present invention is glutaraldehyde. In another embodiment, the fixation reagent of the present invention is an aldehyde. In another embodiment, the fixation reagent of the present invention is dimethylsuberimidate.

In another embodiment, the kit of the present invention comprises a permeability enhancing agents such as detergents. In another embodiment, the permeability enhancing agent of the present invention is saponin. In another embodiment, the permeability enhancing agent of the present invention is tween.

In another embodiment, the kit of the present invention comprises an enzyme conjugated to avidin. a ligand labeled with a hapten. In another embodiment, the kit of the present invention comprises a biotinylated ligand. In another embodiment, the kit of the present invention comprises a label conjugated to avidin. In another embodiment, the kit of the present invention comprises an enzyme conjugated to avidin. In another embodiment, the kit of the present invention comprises an enzyme which creates a detectable event (e.g., chemiluminescent, colorimetric or fluorescent).

In another embodiment, the kit of the present invention comprises alkaline phosphatase. In another embodiment, the kit of the present invention comprises β-galactosidase. In another embodiment, the kit of the present invention comprises peroxidase. In another embodiment, the kit of the present invention comprises horseradish peroxidase.

In another embodiment, the kit of the present invention comprises a secondary labeled antibody specifically identifying the primary antibody.

In another embodiment, the kit of the present invention further comprises a nuclear dye. In another embodiment, the kit of the present invention further comprises Azur A. In another embodiment, the kit of the present invention further comprises hematoxylin. In another embodiment, the kit of the present invention further comprises Methyl Violet. In another embodiment, the kit of the present invention further comprises Phloxine B. In another embodiment, the kit of the present invention further comprises Pyronin Y. In another embodiment, the kit of the present invention further comprises Safranin O. In another embodiment, the kit of the present invention further comprises a cytoplasmic dye. In another embodiment, the kit of the present invention further comprises a cytoplasmic membrane dye. In another embodiment, the kit of the present invention further comprises a nuclear membrane dye. In another embodiment, the kit of the present invention further comprises DAPI (example 1). In another embodiment, the kit of the present invention further comprises a sub-cellular dye as will be readily known to one of skill in the art.

In another embodiment, the kit of the present invention further comprises a multi-well plate. In another embodiment, a multi-well plate of the present invention comprises 96 wells. In another embodiment, a multi-well plate of the present invention comprises 384 wells. In another embodiment, a multi-well plate of the present invention comprises 1536 wells. In another embodiment, a multi-well plate of the present invention comprises from 2-5000 wells. In another embodiment, a multi-well plate of the present invention comprises from 20-3000 wells. In another embodiment, a multi-well plate of the present invention comprises from 96-2000 wells.

In another embodiment, the system of the present invention measures protein synthesis inhibitors.

In another embodiment, the system of the present invention screens protein synthesis inhibitors. In another embodiment, the system of the present invention comprises the kit of the present invention as described hereinabove. In another embodiment, the system of the present invention comprises visualization means. In another embodiment, the system of the present invention tests protein synthesis inhibitors. In another embodiment, the system of the present invention comprises the kit of the present invention as described hereinabove. In another embodiment, the system of the present invention comprises visualization means.

In one embodiment, the system of the present invention comprises an apparatus for exposing the screen of the present invention to a film. In another embodiment, the system of the present invention comprises a fluorescent microscope. In another embodiment, the system of the present invention comprises a confocal microscope. In another embodiment, the system of the present invention comprises a transmission electron microscope. In another embodiment, the system of the present invention comprises a scanning electron microscope. In another embodiment, the system of the present invention comprises a reflection electron microscope. In another embodiment, the system of the present invention comprises a scanning transmission electron microscope. In another embodiment, the system of the present invention comprises a light microscope. In another embodiment, the system of the present invention comprises a charge-coupled device (CCD) camera. In another embodiment, the system of the present invention comprises a back-illuminated, cooled, CCD camera. In another embodiment, the system of the present invention comprises a color CCD camera. In another embodiment, the system of the present invention comprises a dual-photon laser.

In another embodiment, the system of the present invention comprises a fluorometer. In another embodiment, the system of the present invention comprises a computer which digitally records the microscopically captured images. In another embodiment, the system of the present invention comprises a computer which digitally records the CCD camera captured images.

In another embodiment, the system of the present invention comprises computer software.

In another embodiment, the computer software analyzes the digital images collected from at least two fields in each well. In another embodiment, the computer software analyzes the digital images collected from at least three fields in each well. In another embodiment, the computer software analyzes the digital images collected from at least four fields in each well. In another embodiment, the computer software analyzes the digital images collected from at least five fields in each well. In another embodiment, the computer software analyzes the digital images collected from at least six fields in each well. In another embodiment, the computer software analyzes the digital images collected from six fields in each well.

In another embodiment, the system of the present invention comprises computer software based on algorithms for multiple parameters. In another embodiment, the multiple parameters comprise at least two parameters. In another embodiment, the multiple parameters comprise nuclear and cytoplasmic florescent intensities. In another embodiment, the multiple parameters comprise relative nuclear and cytoplasmic florescent intensities. In another embodiment, the multiple parameters comprise nuclear and cytoplasmic chemiluminescent or gold label intensities. In another embodiment, the multiple parameters comprise nuclear and cytoplasmic radioactive label intensities. In another embodiment, the multiple parameters further comprise number, size and signal intensity of SMA complex components. In another embodiment, multiple parameters further comprise number, size and signal intensity of Gems.

EXPERIMENTAL DETAILS SECTION MATERIALS AND EXPERIMENTAL METHODS

Compounds

A library of about 5,000 pure bioactive chemicals that includes FDA-approved drugs, known inhibitors and activators of diverse enzymes and receptors, and pure natural compounds was assembled from commercial sources (Microsource Diversity, Tocris, Sigma/Aldrich and other suppliers). Cycloheximide, trichostatin A, valproic acid and scriptaid were purchased from Sigma Chemical Co. HDAC inhibitor I and apicidin were from EMD biosciences.

Cell Culture and Treatments

HeLa PV were cultured in Dulbecco's modified Eagle's medium (Invitrogen) supplemented with 10% fetal bovine serum (Invitrogen). For screening, cells were seeded onto 384-well plates or, for specific experiments, on glass coverslips the day before treatment. Compounds were added directly into the culture medium to the indicated concentration and the cells were then maintained at 37° C. in a 5% CO2 humidified atmosphere for the duration of the treatment. Dispensing of compounds and other automatic liquid handling steps were performed with a Beckman FX multi-channel system equipped with Hudson Crane robotic systems.

Antibodies

The following mouse monoclonal antibodies were used for indirect immunofluorescence: 2B1 (anti-SMN), 2E17 (anti-Gemin2), 12H12 (anti-Gemin3), 10G11 (anti-Gemin5), 6E2 (anti-Gemin7), 10E10 (anti-PABP), 6BG 10 (anti-FXR1), Y 12 (anti-Sm) and 9H10 (anti-hnRNP A1). An affinity-purified rabbit polyclonal antibody was used to detect Gemin6.

Indirect Immunofluorescence Microscopy

Indirect immunofluorescence on HeLa PV cells was performed as follows: HeLa cells, plated on glass coverslips, were briefly washed with PBS, fixed in 2% formaldehyde/PBS for 20 minutes at room temperature, permeabilized in 0.5% Triton X-100/PBS for 5 min at room temperature. Cells were blocked in 3% bovine serum albumin for 1 hour at room temperature. Double-label immunofluorescence experiments were performed by separate sequential incubations of each primary antibody, diluted in PBS containing 3% bovine serum albumin, followed by the specific secondary coupled to fluorescein isothiocyanate or TXRD. All incubations were at room temperature for 1 hour. Indirect epifluorescence microscopy was performed with a Nikon Eclipse E800 microscope. Digital images were collected with a Cook Sensicam high performance camera and processed with the IP laboratory software. Processing of samples for immunofluorescence microscopy on cells cultured in 384-well plates was automated and performed with the aid of microplate washers (ELX405, Bio-Tek) in a similar manner to that previously used for individual samples on glass slides. The cells were also stained with DAPI to allow definition of the nucleus in each cell. Digital images were acquired with an automated microscopy and analysis system (IN Cell Analyzer 1000, GE Healthcare). Images were analyzed using automated algorithms with parameters set to calculate mean pixel intensity in each nucleus (defined by DAPI staining and acquired in a separate channel), cytoplasm, and total cell, as well as the relevant calculated ratios of these values.

RNA Interference

Transient RNAi was performed as follows: 21-nt RNA duplexes (siRNAs) were designed to target SMN or Gemin2-6 mRNAs. For each target transcript, at least five siRNAs were designed and tested and, in general, found to behave similarly in all subsequent analyses. The following siRNA sequences yielded the most efficient protein knockdowns of each target: GAAGAAUACUGCAGCUUCC (SEQ ID NO: 8) for SMN; GCAGCUCAAUGUCCAGAUG (SEQ ID NO: 9) for Gemin2; GGCUUAGAGUGUCAUGUCU (SEQ ID NO: 10) for Gemin3; ACUCCCCAGUGAGAC CAUU (SEQ ID NO: 11) for Gemin4; GCAUAGUGGUGAUAAUUGA (SEQ ID NO: 12) for Gemin5 and AACUACAGACCCAGUCUCUGC (SEQ ID NO: 13) for Gemin6. In addition, an siRNA initially designed to target Y14, a component of the exon junction complex, which failed to produce any protein reduction within 44 h, was used as a control (CCCGGACCACAACGCUCUG (SEQ ID NO: 14)). All siRNAs were chemically synthesized and purified by Dharmacon Research. Transfections of siRNAs into HeLa PV cells were performed using Oligofectamine™ (Invitrogen) as specified by the manufacturer. Transfected cells were analyzed 40-44 h post-transfection.

Example 1 SMN Complex Composition

In order to determine whether Gems are affected by changes in the composition of the complex, the amount of several Gemins was reduced, one at a time, by RNA interference. The morphology of Gems was monitored by immunofluorescence microscopy using the anti-SMN monoclonal antibody 2B1.

Reduction of Gemin3 or Gemin4 caused large changes in the size, number and SMN signal intensity of Gems (FIG. 1 a). The effect of the treatments was quantified with software analysis of the collected images from a large number of cells. The results indicated a two-fold increase in both signal intensity as well as gem number in each case (FIG. 1 b). Thus, changes in the SMN complex are reflected by changes in the morphology of Gems.

Example 2 Screening Assay

Based on the results obtained in Example 1, a library of ˜5,000 biologically active small molecules was screened on HeLa cells in 384-well plates. Each well was incubated with a different compound (at 10 μM) and the cells were processed for indirect immunofluorescence. Digital images were collected from six fields in each well and analyzed using imaging algorithms for multiple parameters including relative nuclear and cytoplasmic intensities, and number, size and signal intensity of Gems. DAPI-stained images were collected in a separate channel to define the boundary of each nucleus. Images of individual fields in wells were flagged by the software as showing a significant change in SMN sub-cellular localization. These individual wells were examined directly, and active compounds were re-tested for verification (FIG. 2).

Example 3 Redistribution of SMN from the Cytoplasm to the Nucleus

The previous Examples screened compounds that caused changes in Gems. However, it was noticed that several compounds produced a massive redistribution of SMN from the cytoplasm to the nucleus within a relatively short time (2-6 hours) of treatment (according to the materials and methods of example 2). The most striking accumulation of SMN in the nucleus was observed after treatment with the commonly used protein synthesis inhibitor, cycloheximide (CHX). The effect of CHX was evident after only 2 hours of treatment and there was little SMN detected in the cytoplasm after 8 or more hours of treatment. CHX effect on redistribution of SMN from the cytoplasm to the nucleus was concentration-dependent exhibiting a clear effect even at low micromolar concentrations (0.1-40 μM) (FIG. 3 a, b). The nuclear accumulation of SMN did not require complete inhibition of protein synthesis and was proportional to the extent of inhibition of protein synthesis. An inactive cycloheximide analog, cycloheximide-N-ethylethanoate, did not show any effect (FIG. 6).

The accumulation of SMN in the nucleus and its disappearance from the cytoplasm under conditions of protein synthesis inhibition indicates that it represents SMN protein that translocated from the cytoplasm. Other protein synthesis inhibitors, including emetine, an irreversible inhibitor of translation elongation, and the peptide chain terminator, puromycin, showed the same effect as cycloheximide, demonstrating that it is a general consequence of protein synthesis inhibitors (FIG. 6).

The effect of several compounds that do not directly inhibit translation, but rather cause translation inhibition as an indirect effect was monitored. Inducers of endoplasmic reticulum stress, such as thapsigargin and tunicamycin elicit the unfolded protein response, which leads to a reduction in general protein translation through the phosphorylation of eIF2α17. Treatment of cells with thapsigargin or tunicamycin caused SMN to accumulate in the nucleus (FIG. 6B) (, although the effect was not as complete as that seen after treatment with high levels of CHX, consistent with the fact that protein synthesis is not shut down and selective translation of a class of mRNAs continues under these conditions.

Example 4 The Protein Synthesis Inhibitor-Induced Nuclear Accumulation of SMN is Specific

The protein synthesis inhibitor-induced nuclear accumulation of SMN is not the result of general cell toxicity as no reduction in cell viability was monitored even after an overnight treatment of these cells with 10 μM CHX, conditions in which all of the SMN was localized to the nucleus. In addition, the nuclear accumulation is specific to the localization of SMN and not the result of general mis-localization of proteins, as the localization of many other, both nuclear and cytoplasmic proteins that were examined, including the RNA-binding proteins hnRNP A1, poly(A)-binding protein (PABP), FXR1 and snRNPs, was not significantly affected (FIG. 3 c).

Furthermore, the effect was reversible as SMN staining gradually re-appeared in the cytoplasm when cells were washed and placed in fresh medium devoid of cycloheximide. A similar effect of protein synthesis inhibitors was also observed in several other cell types and in other species, including U2OS cells and both human and mouse fibroblasts, and was independent of the amount of SMN they contained. Hela cells with reduced SMN by RNAi, compared to control cells expressing a non-targeting shRNA, showed a similar effect (FIG. 7).

Example 5 Gemins Also Relocate to the Nucleus

According to the materials and methods of Example 2, treated cells were stained with antibodies to each of the Gemins. The results indicate that in addition to SMN, several of the Gemins, with the exception of Gemin3 and Gemin5, also relocated to the nucleus (FIG. 4).

Thus, CHX treatment causes most of the components of the SMN complex to accumulate in the nucleus, and not just SMN alone. This further indicates that the response is a specific effect upon SMN and some associated proteins. Furthermore, the total amount of SMN in HeLa cells treated with CHX was similar to that found in untreated cells, showing that the SMN complexes that accumulated in the nucleus must have been translocated from the cytoplasm.

These observations were made after relatively short treatment times (4-6 hours). However, at longer times (>24 hr), nuclear translocation of SMN was observed for several other compounds. Notably, histone deacetylase (HDAC) inhibitors, including valproic acid (VPA), trichostatin A, scriptaid, apicidin and HDAC inhibitor 1, that caused the same effect as protein synthesis inhibitors (FIG. 5 a).

These compounds showed strong toxicity and resulted in a large reduction in cell numbers. However, they do not cause inhibition of protein synthesis, indicating that their effect on the translocation of SMN works by a different, although possibly convergent, mechanism from that of the protein synthesis inhibitors.

VPA also displayed a clear concentration dependence effect on the nuclear localization of SMN in addition to its specificity in relocalizing a subset of the SMN complex to the nucleus (FIG. 5 b and c). Namely, Gemin3 and Gemin5 remain predominantly cytoplasmic upon a 24 hour treatment with VPA. This further shows that SMN likely responds to these compounds in a similar manner.

Thus these experiments demonstrate that the cellular localization of the SMN complex is a dynamic and highly regulated process. Specifically, reduction in protein synthesis as a result of either direct interaction of inhibitors with the translation machinery or indirectly, as a consequence of ER stress, profoundly affects the SMN complex, translocating SMN and several of the complex components to the nucleus.

Although both translation inhibitors and HDAC inhibitors show a similar effect, the former class of compounds elicited the most rapid responses. The noticeable increase in the amount of the an SMN complex component in the nucleus, even at low doses of inhibitor that produce only a very small reduction in overall translation, indicates that even mild stresses that attenuate translation have an effect on the balance of the SMN complex.

It appears that the SMN complex either dissociates into Gemin3/5 and SMN, Gemin2, 6, 7 subunits upon inhibition of translation or these subunits are already mostly in the dissociated form and their localization in the cell is regulated differently. 

1. A method for testing a candidate compound for an ability to inhibit protein synthesis in a cell, comprising the steps of: contacting said cell with said candidate compound; and measuring the level of a SMN complex component in the cytoplasm of said cell, the nucleus of said cell, or a combination thereof, whereby, if said candidate compound increases the amount of the SMN complex component in said nucleus, decreases the amount of the SMN complex component in said cytoplasm, or a combination thereof, then said compound exhibits an ability to inhibit protein synthesis.
 2. The method of claim 1, wherein said cell is a eukaryotic cell.
 3. The method of claim 1, wherein said method further comprises the step of contacting said cell with a ligand selective for said SMN complex component.
 4. The method of claim 3, wherein said ligand is an antibody.
 5. The method of claim 4, wherein said antibody is a monoclonal antibody.
 6. The method of claim 4, wherein said antibody is a labeled antibody.
 7. The method of claim 6, wherein said labeled antibody is a fluorescent labeled antibody.
 8. The method of claim 3, wherein said ligand is a labeled ligand.
 9. The method of claim 8, wherein said labeled ligand is a fluorescent labeled ligand.
 10. The method of claim 1, wherein said SMN complex component is fused to a fluorescent probe
 11. The method of claim 1, wherein said SMN complex component is a Gem.
 12. The method of claim 1, wherein said SMN complex component is a Gemin.
 13. The method of claim 12, wherein said Gemin is Gemin 2, Genin 6, Gemin 7, or any combination thereof.
 14. The method of claim 1, wherein the step of measuring comprises the use of visualization means to identify said SMN complex components.
 15. The method of claim 14, wherein said visualization means comprise a microscope.
 16. The method of claim 14, wherein said step of visualization of said SMN complex component further comprises the use of digital images.
 17. The method of claim 16, wherein said digital images are analyzed using imaging algorithms for parameters comprising nuclear signal intensity and cytoplasmic signal intensity.
 18. A method for testing a candidate compound for an ability to inhibit protein synthesis in a cell, comprising the steps of: contacting said cell with said candidate compound; and measuring a level of an SMN complex component in the nucleus of said cell, whereby, if said candidate compound increases the amount of the SMN complex component in said nucleus then said compound exhibits an ability to inhibit protein synthesis. 19-34. (canceled)
 35. A kit for screening a protein synthesis inhibitor in a cell, comprising a means of measuring a relocation of an SMN complex component in said cell.
 36. (canceled)
 37. The kit of claim 35, wherein said means comprise a ligand selective for a SMN complex component.
 38. The kit of claim 37, wherein said ligand is an antibody. 39-51. (canceled) 